SYNOPSIS. 423 



Hie hinder part of the body forming a dorsal, anal, and caudal 

 fins. 



Sp. 248. P. marinus. Lamprey. Body eel-like, compressed 

 and slightly tapering behind ; two dorsal fins, the second 

 most elevated, and separated from the caudal ; skin smooth, 

 the colour olive-brown mottled and spotted with dark 

 green and dark brown ; edges of the fins reddish brown. 

 Linn., Penn. Brit. Zool, iii. p. 102, pi. 10 ; Don. Brit. 

 Fish, pi. 81 ; Yarr. Brit. Fish., ii. 598. 

 Sp. 249. P. flumatilis. River Lamprty. Body more elon- 

 gated in proportion than that of P. marinus; end of the 

 tail compressed ; dorsals widely apart, the posterior one 

 angular and united to the caudal ; anal also united to the 

 caudal ; colour dusky blue above, silvery white beneath. 

 Linn., Guv. Rey. An. Lesser lamprey, Penn. Brit. Zool., 

 iii. p. 106, pi. 10 ; Don. Brit. Fish., pi. 54; Yarr. Brit. 

 Fish., ii. 604. 



Sp. 250. P. Planeri. Planer's Lamprey. Lip broad and 

 fringed ; first dorsal beginning about the middle of the 

 whole length of the fish, and in close contact with the 

 second ; anal fin rudimentary ; colours nearly as in P. 

 flwiatilis. Bloch, pt. iii., pi. 78, fig. 3; Jenytta* Brit. 

 Vert., 522 ; Yarr. Brit. Fish., ii. 607. 

 GEN. CXXIII. AMMOCCETES. Each side of the neck with 

 seven branchial openings ; lip semicircular, under lip straight 

 and transverse ; teeth wanting, their place supplied by mem- 

 branous cirri. 



Sp. 251. A. branchialis. Pride or Mud Lamprey. Eye 



very small ; body cyiifuric&l, compressed behind the anal 



opening ; two dorsals, first low, separated from the second ; 



caudal rather rounded ; colour yellowish brown, darkest 



on the back and lighter beneath, but liable to variation. 



Cuv. Reg. An. ; Jenyns' Brit. Vert., 522; Yarr. Brit. 



Fish., ii. 609. Petromyzon branchialis, Linn. 



GEN. CXXIV. GASTROBRANCHUS. Branchial openings tw.j 



in number, placed under the commencement of the belly ; lips 



surrounded with eight cirri, the mouth with one hook-like 



tooth ; tongue with two rows of teeth on each side. 



